This invention relates to chambers for hyperbaric oxygen therapy. Hyperbaric oxygenation is a mode of medical treatment in which the patient is entirely enclosed in a pressure chamber breathing oxygen at a pressure greater than one atmosphere.
Hyperbaric oxygen therapy began during the 1930's with Navy studies on the use of oxygen to more rapidly decompress divers and to treat those divers suffering from decompression sickness. Since that time, studies on the efficacy and proper utilization of hyperbaric oxygen therapy have greatly expanded the role of hyperbaric oxygen therapy in modern medicine.
Besides being essentially the only accepted treatment for decompression sickness, hyperbaric oxygen therapy has also become accepted as a primary or adjunctive therapy for decubitus ulcers, radiation necrosis, acute carbon monoxide poisoning, acute gas embolism, gas gangrene, refractory osteomyelitis, crush injuries with acute traumatic ischemia, acute cyanide poisoning and acute cerebral edema. Furthermore, studies are presently being conducted to determine the efficacy of hyperbaric oxygen therapy in the treatment of thermal burns, bone grafting, acute carbon tetrachloride poisoning, fracture healing, multiple sclerosis, sickle cell anemia and numerous other conditions.
The cost of hyperbaric oxygen therapy limits its use in treating the conditions for which hyperbaric oxygen therapy has proved to be effective, and drastically limits the scope of studies into further potential benefits from hyperbaric oxygen therapy. Typically, a patient undergoes hyperbaric oxygen therapy for a period of about an hour while lying within a mono-place chamber pressurized with pure oxygen, or while sitting or standing within a multi-place chamber pressurized with compressed air while breathing pure oxygen through a mask.
Mono-place hyperbaric oxygen chambers are generally elongate, horizontal cylinders pressurized with pure oxygen in which the patient must lie in the prone position. Although these mono-place chambers are considerably less expensive to construct and operate than the larger multi-place chambers, they are still relatively expensive. This is due to the expense involved in manufacturing an outwardly opening door mechanism which is capable of maintaining a proper seal while the chamber is pressurized and the cost of fabricating and maintaining the double-walled plastic cylinder used to form the chamber.
Mono-place hyperbaric oxygen chambers are also expensive to operate. Since patients are slid into the end of mono-place chambers on a gurney, the room used to house the chamber must be longer than the length of the chamber plus the length of the gurney. This space requirement typically makes it impractical for small clinics or individual physicians to administer hyperbaric oxygen therapy.
One of the major costs involved in treating a patient with hyperbaric oxygen therapy in a mono-place chamber is the cost of the oxygen. Since the entire mono-place chamber is pressurized with oxygen, and since the safety and comfort of the patient requires that the chamber be constantly ventilated, the minimum oxygen usage for such a chamber is about 240 liters per minute. However, since the only cooling typically available to offset the accumulation of body heat in the chamber is from the flow of oxygen in the chamber, oxygen usage is often as high as 500 liters per minute. The total oxygen environment of the mono-place chambers also necessitates the inclusion of variety of safety features. Substantial ventilation systems are required to ensure against carbon dioxide accumulation in the chamber. Furthermore, because of the increased flammability of most materials in a pure oxygen environment, there is always the potential for a catastrophic fire.
One example of a mono-place hyperbaric oxygen chamber is disclosed in U.S. Pat. No. 3,587,574, issued Jun. 28, 1971 to Mercer, in which an elongated tubular hermetically sealable casing having a pressure sealable door at each end and a floor structure has internal supports for a patient's bed or litter. A similar example of a transportable hyperbaric chamber is disclosed in U.S. Pat. No. 4,467,798, issued Aug. 24, 1984 to Saxon et al., in which a cylindrical chamber is adapted to be temporarily connected to a deck chamber or other emergency chamber to receive an injured person.
Another approach is disclosed in PCT Publication PC/SE79/00011, issued Aug. 9, 1979 to Ingelstedt, et al., in which a pressure sealed, rotating chamber with a cylindrical pressure-tight door on one end is used to rotate a patient to a reclined or upright sitting position for the treatment of middle ear dysfunction.
Each of these examples has a disadvantage in that they use heavy, externally mounted pressure doors to seal the chamber. these doors are expensive to manufacture and difficult to mount and operate.
Other references consulted regarding structural features but not deemed pertinent to the present invention as claimed are U.S. Pat. No. 2,292,092, issued Aug. 4, 1942 to Shankweller ("Cabinet Cover") and U.S. Pat. No. 1,169,143, issued Jan. 25 1916 to Furlong ("Door").
Treatments in mono-place hyperbaric oxygen chambers are generally disliked by patients. The patients find it very uncomfortable to lie on their backs in the chambers for the long periods required by the therapy. In addition, to the physiological discomfort caused by the treatments, patients typically experience enhanced feelings of claustrophobia during the sessions.
Although multi-place chambers are significantly more comfortable than mono-place hyperbaric oxygen chambers, in that they permit the patient to sit or stand during the treatment session, these large chambers suffer many drawbacks. Due to the size of the chambers, they cannot be prefabricated and shipped to a facility, but must be custom fabricated on site. Typically, the large chambers also require a large support staff. Due to their size and the expense involved in their manufacture, multi-place chambers are only utilized at relatively large facilities, which deal with a large number of cases wherein hyperbaric oxygen therapy is the only accepted mode of treatment. Even at these facilities, the cost of each individual therapy session greatly limits the use of hyperbaric oxygen therapy.
In view-of the foregoing, a need exists for a safe, comfortable mono-place hyperbaric oxygen chamber which is relatively inexpensive to manufacture and operate.